1. Field of the Invention
This invention generally relates to a bicycle component calibration device or method for a bicycle component that is movable between at least two positions. More specifically, the present invention relates to a bicycle component calibration device or method that adjusts an electric bicycle component (e.g., electrically controlled bicycle derailleur) to a correct position (e.g., correct shifting position).
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle. In particular, the bicycle transmission has been significantly changed over the years.
Derailleur operated bicycle transmissions typically comprise a plurality of sprockets that rotate with another rotating member (e.g., the front crank and/or the rear wheel of the bicycle) and a derailleur that is used to shift a chain among the plurality of sprockets. Conventional derailleur transmissions were manually controlled by a hand operated actuator such as a lever or twist-grip attached to the bicycle handlebar, wherein the derailleur is connected to the actuator by a Bowden cable.
Recently, bicycles have been equipped with electrical components to make riding easier and more enjoyable for the rider. Some bicycles are equipped with electrically controlled shifting systems. In particular, in theses electrically controlled shifting systems, the front and rear derailleurs are provided with motors that move the chain guide to obtain the various gear positions. A common operating parameter is the position of the derailleur relative to the plurality of sprockets. In the past, potentiometers that cooperated with various moving components of the derailleur were used to ascertain the position of the derailleur. Since derailleurs usually have a relatively small range of motion, high precision potentiometers were required for this purpose. That was especially true when the information provided by the potentiometer is used by an electronic device to shift the chain among the plurality of sprockets. Unfortunately, high precision potentiometers are relatively expensive, thus making electronically controlled derailleurs using high precision potentiometers unsuitable for mass production. Inexpensive potentiometers have nonlinear characteristics, and such characteristics vary from one potentiometer to another. Thus, the actual derailleur position is difficult to ascertain with such potentiometers, and the unpredictability from one potentiometer to another also makes derailleurs using such potentiometers unsuitable for mass production. Some examples of electrical controlled bicycle derailleurs are disclosed in U.S. Pat. No. 6,945,888 to Fukuda et al. (assigned to Shimano Inc.) and U.S. Pat. No. 7,306,531 to Ichida et al. (assigned to Shimano Inc.). In these conventional electrically controlled bicycle derailleurs, an analog position sensor and a digital position sensor are used to control the shift position of the derailleur.
In particular, in U.S. Pat. No. 7,306,531, the electrical controlled bicycle derailleur uses an analog position sensor formed by a potentiometer in order to detect a position of the an output shaft of a motor drive train of a motor, and a digital position sensor formed by a shutter wheel and a photo interrupter in order to detect both the rotational direction and the angular position of the output shaft of the motor drive train of the motor.
In generally, when the electrical controlled bicycle derailleur disclosed in U.S. Pat. No. 7,306,531 is being calibrated, an adjusting mode is used that adjusts the output shaft of the motor drive train step by step using one digital step (one pulse) of the digital position sensor. This very small adjustment is very useful in obtaining good shifting performance, especially in the case of competition. However, since each adjustment increment (step) results in a very small amount of movement of the chain guide, some riders could not determine (confirm) if the adjustment was made or not. In addition, due to the small amount of movement with each adjustment increment, it is also sometimes difficult for the rider to determine which direction the chain guide is being moved. Thus, some riders may over adjust the derailleur, or adjust the derailleur in the wrong direction.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved bicycle component calibration device or method. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.